28,285 research outputs found
Double vector meson production in the International Linear Collider
In this paper we study double vector meson production in
interactions at high energies and, using the color dipole picture, estimate the
main observables which can be probed at the International Linear Collider
(ILC). The total
cross-sections for , , and are computed
and the energy and virtuality dependencies are studied in detail. Our results
demonstrate that the experimental analysis of this process is feasible at the
ILC and it can be useful to constrain the QCD dynamics at high energies.Comment: 11 pages, 8 figure
Fast gates for ion traps by splitting laser pulses
We present a fast phase gate scheme that is experimentally achievable and has an operation time more than two orders of magnitude faster than current experimental schemes for low numbers of pulses. The gate time improves with the number of pulses following an inverse power law. Unlike
implemented schemes which excite precise motional sidebands, thus limiting
the gate timescale, our scheme excites multiple motional states using discrete
ultra-fast pulses.We use beam-splitters to divide pulses into smaller components
to overcome limitations due to the finite laser pulse repetition rate. This provides
gate times faster than proposed theoretical schemes when we optimize a practical
setup
Anderson localization on the Falicov-Kimball model with Coulomb disorder
The role of Coulomb disorder is analysed in the Anderson-Falicov-Kimball
model. Phase diagrams of correlated and disordered electron systems are
calculated within dynamical mean-field theory applied to the Bethe lattice, in
which metal-insulator transitions led by structural and Coulomb disorders and
correlation can be identified. Metallic, Mott insulator, and Anderson insulator
phases, as well as the crossover between them are studied in this perspective.
We show that Coulomb disorder has a relevant role in the phase-transition
behavior as the system is led towards the insulator regime
Polarimetry of Compact Symmetric Objects
We present multi-frequency VLBA observations of two polarized Compact
Symmetric Objects (CSOs), J0000+4054 and J1826+1831, and a polarized CSO
candidate, J1915+6548. Using the wavelength-squared dependence of Faraday
rotation, we obtained rotation measures (RMs) of -180 \pm 10 rad m^-2 and 1540
\pm 7 rad m^-2 for the latter two sources. These are lower than what is
expected of CSOs (several 1000 rad m^-2) and, depending on the path length of
the Faraday screens, require magnetic fields from 0.03 to 6 \mu G. These CSOs
may be more heavily affected by Doppler boosting than their unpolarized
counterparts, suggesting that a jet-axis orientation more inclined towards the
line of sight is necessary to detect any polarization. This allows for low RMs
if the polarized components are oriented away from the depolarizing
circumnuclear torus. These observations also add a fourth epoch to the proper
motion studies of J0000+4054 and J1826+1831, constraining their kinematic age
estimates to >610 yrs and 2600 \pm 490 yrs, respectively. The morphology,
spectrum, and component motions of J1915+6548 are discussed in light of its new
classification as a CSO candidate, and its angle to the line of sight (~50\deg)
is determined from relativistic beaming arguments.Comment: 29 pages, including 9 figures; Accepted by Astrophysical Journal, 16
Feb 0
Bayesian Non-Exhaustive Classification A Case Study: Online Name Disambiguation using Temporal Record Streams
The name entity disambiguation task aims to partition the records of multiple
real-life persons so that each partition contains records pertaining to a
unique person. Most of the existing solutions for this task operate in a batch
mode, where all records to be disambiguated are initially available to the
algorithm. However, more realistic settings require that the name
disambiguation task be performed in an online fashion, in addition to, being
able to identify records of new ambiguous entities having no preexisting
records. In this work, we propose a Bayesian non-exhaustive classification
framework for solving online name disambiguation task. Our proposed method uses
a Dirichlet process prior with a Normal * Normal * Inverse Wishart data model
which enables identification of new ambiguous entities who have no records in
the training data. For online classification, we use one sweep Gibbs sampler
which is very efficient and effective. As a case study we consider
bibliographic data in a temporal stream format and disambiguate authors by
partitioning their papers into homogeneous groups. Our experimental results
demonstrate that the proposed method is better than existing methods for
performing online name disambiguation task.Comment: to appear in CIKM 201
- …